---
name: "memcachedb"
section: "1"
platform: "linux"
package: "memcachedb"
version: "1.2.0-12"
release: "Debian 9 (Stretch)"
platforms: ["linux"]
url: "https://new.carta.tech/memcachedb"
---

# memcachedb(1)

persistence-enabled variant of memcached

## NAME

memcachedb - persistence-enabled variant of memcached

## SYNOPSIS

**memcachedb** \[*OPTIONS*\]

## DESCRIPTION

MemcacheDB (pronounced *mem-cash-dee-bee*) is a persistence-enabled variant of the **memcached** distributed key-value storage system. It is NOT a cache solution, but rather a persistent storage engine for fast and reliable key-value based object storage and retrieval.

It conforms to the **memcache** protocol, which means that *memcached* clients can connect and use the persistent key-value store transparently. It also provides reliability and high-availability through its transaction and replication support, courtesy of its BerkeleyDB storage backend.

## OPTIONS

- `-p` \<num\>

  TCP port to listen on  (default: 21201)

- `-U` \<num\>

  UDP port to listen on (default: 0, off)

- `-s` \<file\>

  UNIX Domain Socket path to listen on (disables network support)

- `-a` \<mask\>

  Access mask for unix socket, in octal (default: 0700)

- `-l` \<ip\_addr\>

  Interface to listen on (default: INADRR\_ANY)

- `-d`

  Run as a daemon

- `-r`

  Maximize core file limit

- `-u` \<username\>

  Assume identity of \<*username*\> (only when run as root)

- `-c` \<num\>

  Maximum simultaneous connections (default: 4096)

- `-b` \<num\>

  Item size smaller than \<*num*\> bytes will use fast memory allocation (default: 2048 bytes)

- `-v`

  Verbose (print errors/warnings while in event loop)

- `-vv`

  Very verbose (also print client commands/reponses)

- `-h`

  Print brief usage instructions and exit

- `-i`

  Print complete copyright and license information

- `-P` \<file\>

  Save process ID in \<*file*\> (only used with the -d option)

- `-t` \<num\>

  Number of threads to use (default: 4)

### Berkeley DB Options

- `-m` \<num\>

  In-memory cache size of BerkeleyDB in megabytes (default: 256MB)

- `-A` \<num\>

  Underlying page size in bytes (default: 4096, range: 512B-64KB, power-of-two)

- `-f` \<file\>

  Filename of database (default: *data.db*)

- `-H` \<dir\>

  Environment HOME of database (default: */data1/memcachedb*)

- `-G` \<dir\>

  Log directory of database (default: same as Environment HOME, see -H)

- `-B` \<db\_type\>

  Type of database, options are: 'btree' or 'hash' (default: btree)

- `-L` \<num\>

  Log buffer size in kBytes (default: 4096kB)

- `-C` \<num\>

  Perform a checkpoint every \<*num*\> seconds (0 to disable, default: 300 seconds)

- `-T` \<num\>

  Do **memp\_trickle** every \<*num*\> seconds (0 to disable, default: 30 seconds)

- `-e` \<num\>

  Percentage of the pages in the cache that should be clean (default: 60%)

- `-D` \<num\>

  Perform deadlock detection every \<*num*\> milliseconds (0 to disable, default: 100ms)

- `-N`

  Enable **DB\_TXN\_NOSYNC** for a large performance gain (default: off)

- `-E`

  Automatically remove log files that are no longer needed

- `-X`

  Allocate region memory from the heap (default: off)

### Replication Options

- `-R`

  Identifies the host and port used by this site (required)

- `-O`

  Identifies another site participating in this replication group

- `-M`/`-S`

  Start memcachedb as a master or slave

- `-n` \<num\>

  Number of sites participating in replication (default: 2)

## CAVEATS

- •

  Because this is a persistent storage solution, expire time specified in the corresponding memcache protocol clients will be silently discarded.

## FILES

- `/etc/memcachedb.conf`

  ## SEE ALSO

[memcached(1)](/memcached/1.md)

## AUTHOR

MemcacheDB was written and is maintained by Steve Chu \<stvchu@gmail.com\>, based on Memcached by Danga Interactive, Inc. \<http://www.danga.com/\>